This invention relates to a cam shaft locking device for preventing the rotation of the cam shaft of a fuel injection pump for an internal combustion engine during the transportation of the fuel injection pump and while mounting same on the engine.
When a fuel injection pump is mounted on an engine, the cam shaft of the fuel injection pump should be connected to the crank shaft of the engine in an optimum rotational position of the cam shaft so as to obtain injection of the fuel during the appropriate stroke of the engine. In conventional fuel injection pumps, a difficulty has hitherto been encountered in maintaining the cam shaft in an optimum rotational position with respect to the pump body because the cam shaft rotates to its most stable position while being transported or mounted on the engine. To overcome this difficulty, it has hitherto been usual practice to put a mark (line) to the coupling block connected to the cam shaft and the pump body for indicating an optimum rotational position of the cam shaft. In mounting the pump on the engine, the cam shaft is rotated until these two marks accord with each other, and the coupling block is connected to the driving member of the engine, so as to thereby optimally adjust the relative positions of the cam shaft of the fuel injection pump and the crank shaft of the engine. When this process is adopted, it is necessary to bring the marks into accord with each other in mounting the fuel injection pump on the engine, making the pump mounting operation troublesome. Particularly, the fuel injection timing adjusting operation is time-consuming because the marks are sometimes hidden behind parts of the engine.